BUENOS AIRES: A trial involving almost 800 cases of human rights abuses during Argentina's 1976-1983 military junta got under way Wednesday, chronicling the use of torture and murder during the dictatorship.

The trial in Buenos Aires, "was, is and will be the largest trial of crimes against humanity" in Argentina, said rights attorney Rodolfo Yanzon.

The trial, on 789 documented abuse cases, is the largest in the South American nation since 2003. It is being held in a packed Buenos Aires courtroom, presided over by Judge Daniel Obligado, as rights activists outside waved signs demanding justice be done, decades on.

The trial is expected to take about two years, and may bring in as many as 900 witnesses.

Among the accused are, for the first times, men who piloted "death flights" on which abducted leftists opposing the regime, or thought to oppose it, were tossed alive into the Rio de la Plata, in the belief they would be killed without a trace.

Some 30,000 people were kidnapped, tortured and killed in what became known as Argentina's "Dirty War," according to rights groups. Victims included Montonero guerrillas, labor union leaders, students, leftist sympathizers and in some instance, their relatives and friends.

The trial is part of an effort to probe torture and crimes against humanity committed at a notorious ESMA Naval Mechanics School. Only a fraction of the estimated 5,000 regime opponents survived being sent to ESMA.

Among the cases on trial is that of Leonie Duquet, a French-born nun who was allegedly kidnapped and killed on a "death flight."

The bodies of Duquet and three members of the Mothers of the Plaza de Mayo -- a rights group helping regime victims -- washed up on a beach in Buenos Aires province in 1977. Locals initially buried the women under headstones that read "SN," or "sin nombre" -- "no name."

The trial's defendants include eight "death flight" pilots -- among them is Julio Poch, a Dutch national and a former Argentine naval aviator extradited from Spain in May 2010.

Until his arrest Poch was working as a pilot for Transavia, a subsidiary of Air France and KLM. His work colleagues turned him in when Poch recounted stories from his days in the Argentine navy.

Other defendants include former navy captain Alfredo Astiz, the "Blonde Angel of Death," who allegedly helped kidnap four members of the Mothers rights group, including its founder Azucena Villaflor, as well as Duquet and Alice Domon, another French nun who is still missing.

An Argentine court sentenced Astiz to life in prison for torture, murder and rights abuses in October 2011.

Pro-junta civilians will also be on trial, including former finance minister Juan Alemann, who allegedly witnessed the torture of a man suspected of attempting to murder him.

A blanket pardon for dictatorship crimes was overturned in 2003, paving the way for lawsuits.

In September a Crimes Against Humanity Board report found that between 2008 and July 2012 there were 61 trials for crimes committed by the military dictatorship, with 270 convictions.